Water cooled and moderated nuclear power reactors are well-known and are discussed, for example, by M. M. El-Wakil in "Nuclear Power Engineering" McGraw-Hill Book Company, Inc., 1962.
Fuel elements for such reactors typically are in the form of uranium oxide and/or plutonium oxide pellets contained in a protective, elongated cladding tube formed of a suitable metal, commonly a zirconium alloy such as Zircaloy-2. Such a fuel element is shown, for example, in U.S. Pat. No. 3,365,371.
To prevent premature failure of the fuel element cladding and to extend its useful mechanical life, various protective barriers between the column of fuel pellets and the inner surface of the cladding have been proposed. Among these barriers are layers of zirconium metal bonded to the inner surface of the zirconium alloy of the cladding tube.
In copending patent application Ser. No. 727,183, filed Sept. 27, 1976, now abandoned in favor of continuation application Ser. No. 014,348, filed Feb. 23, 1979, now U.S. Pat. No. 4,372,817, and in continuation-in-part application Ser. No. 838,161, filed Sept. 30, 1977, and now U.S. Pat. No. 4,200,492, each assigned to the same assignee as this invention, there is described a barrier layer formed of substantially pure zirconium metal bonded to the inner surface of the cladding tube.
In copending patent application Ser. No. 838,161, filed Sept. 30, 1977, now U.S. Pat. No. 4,200,492 and assigned to the same assignee as this invention, there is described a barrier layer formed of zirconium metal of moderate purity such as sponge zirconium.
An object of this invention is a method of forming a layer of zirconium metal on the inner surface of a fuel element cladding tube with enhancement of the characteristics of the zirconium layer as a protective barrier.